Golf is a popular sport which has been played in many countries throughout the world and is increasing in popularity with young and old since the advent of televised tournaments.
The game challenges golfers to acquire precision and maintain ball hitting skills with a variety of clubs, on balls which may, be on a tee, virtually buried in a trap, or anything in between. Thus, delicate timing, tempo, proper swing, stance, balance, and grip are necessary to achieve the control required to make good shots with reasonable consistency. No human with his or her inherent physical limitations combined with golf's companion mental strains and insidious variables, can seriously expect perfect execution of every shot, every time.
To play well, proper instruction and considerable practice are required. This is usually followed by intermittent periods of analysis of repetitive errors, followed by more practice including corrective measures etc. and the cycle is then repeated many times.
Many amateur players appear to concentrate their practice efforts on attempts to hit long straight drives, and accordingly, go to golf driving ranges where actual shots may be observed. Chip-and-putt courses also have this actual ball flight observation benefit. Unfortunately, these practice facilities are not always easily accessible and, in addition, their use is dependent on open-for business hours and weather conditions.
To circumvent the above limitations, many tethered ball hitting practice devices have been developed in recent years. These vary in complexity and intent. The relatively simple devices consist of a practice ball tethered by a cord to a spike driven into the ground. With such a device the user primarily practices his swing and the associated factors. A more sophisticated tee shot practice device is described in U.S. Pat. No. 4,609,197. This device tees the ball on top of a hollow (in the ground) spike which contains the tether shock cord and has an impact measuring device attached to the upper end of the spike. Thus, the user has an additional indication of the club-to-ball impact power.
Two more versatile and sophisticated golf practice devices are described in U.S. Pat. No. 4,118,032 and U.S. Pat. No. 4,139,197. These practice devices contain distance and direction scales which are staked to the ground and connected by a tether cord, to the practice ball a few feet away, thus the user of these devices has additional information to evaluate the quality of his practice strokes. The main disadvantages of these practice devices are that, first their uses are limited to ground type areas where stakes or spikes can be driven and second, their gauges and scales function by a sequence of activity by springs, pivots, drums, brakes guides, and other active mechanical parts which are not only costly to manufacture but also subject to malfunction caused by moisture, dirt, and the other elements of an outdoor environment.
A golf practice device which circumvents the above disadvantages is titled, "GOLF PRACTICE DRIVE ANALYSER," and is described in U.S. Pat. No. 4,071,250. This device has only four essential parts. The driving ball is anchored to one end of a mat, which has distance marker indicia across the mat surface, by a tether which has two parts. The anchor end of the tether is a chain made of links of uniform weight and length. The chain links are positioned across the full scale of marker indicia on the mat and terminate on the "0" yard marker. The second end of the tether consists of a substantially weightless flexible cord which connects the "0" marker link of the chain to the practice ball which is positioned a few feet away. When hit by the driving golf club, the ball travels over the mat in a brief free flight which is gradually reduced in velocity as the uniformly weighted chain is picked up thereby absorbing the kinetic energy of the ball before the full length of the chain is used. The position and length of the displaced tether chain laying on the mat indicate the direction and distance of the simulated flight of the ball.
One disadvantage in the use of the above-described device is the probable safety hazard involved. Since the very safe lightweight (.sup.1/2 ounce or so) perforated plastic or cotton practice balls do not have the inertia on their flight trajectories to displace even a light chain, something heavier would have to be used to fill the chain displacement requirements. Thus, if the substantially weightless flexible segment of the tether cord was caught between the ball and the sharp bottom of a club face during impact and cut, a potentially hazardous situation might be caused by the run-away ball.
In general, an additional disadvantage of all the practice devices described is that their inherent physical characteristics limit their distance readout resolution to only one scale. For example, these devices may clearly indicate the stroke quality differences between a 150 yard drive and a 200 yard drive, but the same device cannot determine or resolve the quality differences between 25 yard and 20 yard chipping strokes.